Who is Participating?

Sure, Safari has Developer tools. Click the Web Inspector under Develop.1. Click the Debugger. Navigate to the Javascript.
2. Click Pause (Pause becomes Play).
3. Use the Step Out, Step Over, Step Into buttons to navigate through the Javascript.
4. Current position in the code.
5. Variable values show up on the right.
6. Set Breakpoints and press the Play button to advance the cursor to that point.